Electron discharge device



April 1941- A. J. w. M. VAN OVERBEEK .2 v

\ ELECTRON DISCHARGE DEVICE Filed April 26, 1939 INVENTTOR. ADRIAN S J.W.M- VAN OVERBEEK ATTORNEY.

Patented Apr. 1, 1941 UNITED STATES 2,236,860 ELECTRON DISCHARGE DEVICE Adrianus Johannes Wilhelmus Marie van Overbeek, Eindhoven, Netherlands, assignor to N. V.

Philips Gloeilampenfabrieken,

Eindhoven,

Netherlands, a corporation of the Netherlands Application April 26 1939; Serial No. 270,050

In Germany May 13, 1938 7 Claims. .(Cl. 250-275) This invention relates to an electric discharge device particularly suitable for superheterodyne reception and comprising an electrode system, in which the electrons issuing from the cathode are split up into two or more beams and at least one of these beams emerges through an aperture of a plate-shaped electrode into another part of the discharge space to an output electrode. In the present case the current of electrons may, for instance, be split up into four beams, two of which are directed to an oscillator anode inside the plate-shaped screen electrode, whereas two other beams emerge through apertures of this plateshaped electrode and successively traverse a con trol grid, a screen grid and an anode.

Particularly in the last mentioned case, in which the beams emerging through one or more apertures traverse a control grid, being the first succeeding electrode, it is important in order that the slope of the characteristic curve be as steep as possible, that the electrons should approach this grid approximately at right angles. However, in this case substantially all of the electrons reversing their direction in front of this grid when it swings sumciently negative return through the apertures of the screen electrode to the vicinity of the cathode and control grid contained therein.

It has already been suggested to provide one or more rod-shaped electrodes in the space between I the apertures of the plate-shaped electrode at the first succeeding grid, by which electrodes the electrons are deflected and the electron beam moving to the anode split so that the electrons no longer approach at right angles to this grid so that they no longer return on radial lines to the inside of the screen electrode. Another expedient to attain the same purpose is to give the first grid after the screen electrode a smaller curvature at the parts not opposite the apertures of the screen electrode than at the remaining parts of this grid.

Although these expedients prevent the returning electrons from gaining access to the interior of the screen electrode, this is only possible by tolerating another defect. The presence, for instance, of a rod-shaped electrode in the paths of the electrons causes non-uniform fields between the grid and other electrodes, whereas a grid having various curvatures involves difiiculties from v the point of view of manufacture.

The object of the present invention is to provide means to prevent, the electrons from returning inside the screen electrode without the further properties of the tube being substantially altered.

In a discharge tube according to the invention, whose electrode system includes a plate-shaped screen electrode having one or more apertures through which the electrons emitted by the oathode emerge in the form of beams and traverse one or more grid shaped electrodes on their way to the anode, the first grid electrode which has a regular shape, for instance a circular or elliptical shape, is arranged in such a manner that the center lies beyond the plane of symmetry which extends through the cathode and the apertures of the plate shaped electrode. That is the axis of this grid and the plate shaped electrode are laterally displaced. As a result the electrons have a certain tangential movement due to the electrostatic field which results and do not return through the apertures of the screen electrode, but aredeflected to the space in a region outside this aperture. According to one form of construction of the present invention, a collecting electrode can be arranged in the region of concentration of the returning electrons. Such a construction may, for instance, advantageously be used in a phase converter.

According to one form of construction of the present invention the grid thus arranged constitutes the input control grid of a mixing tube in which the electrons issuing from the cathode are united into four-beams, two of which are directed through a grid which closely surrounds'the cathode and eiiects the beam formation, two beams being directed to an oscillator anode inside the plate-shaped screen electrode, and two other beams emerging through apertures in this screen electrode and successively traversing a control grid, arranged according to the invention, a screen grid, and if desired a suppressor grid, and passing to an anode.

The novel features which I believe to be characteristic of my invention are set forthwith particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figure l is a top endview of one form of an electron discharge device made according to my invention and Figure 2 is a top end view of a modification of the structure shown in Figure 1.

In the drawing an indirectly heated cathode I is surrounded by a grid 2 which is secured to rods 3 afiecting the formation of the four beams of electrons. A plate-shaped screen electrode 4 preferably of sheet material having two apertures 5 directly adjoins these rods. Within this screen electrode are provided two plate-shaped electrodes cathode and grid and the plate-shaped screen electrode but will concentrate at a point beyond this electrode.

As has already been set out above a separate collectingv electrode, which may have a definite function in certain tube constructions, may be arranged at a point where these electrons return. The difference between the structure shown in Figure 1 and Figure 2 is the added electrode I0 which may have applied to it such a positive potential that it will collect the electrons returned by the control grid! when it swings sumciently negative, the greater part of the electrons returned by this grid being absorbed by the electrode l0.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

1. An electron discharge device having a cathode for emitting electrons and an output anode for receiving electrons from said cathode, a control grid surrounding said cathode, and'means for forming said electrons into a plurality of radial beams, a shield electrode positioned around said provided with an aperture registering with one of said beams, anotherof said beams being directed within the said shield electrode and an auxiliary anode positioned between said grid and shield in the path of the beam directed within the shield electrode toreceive electrons from said beam, and a second control electrode between said shield and output anode, said output anode and second control electrode being symmetrically shaped and eccentrically positioned with respect to the aperture in said shield electrodewhereby the electric field between the shield electrode and second control grid during operation of the tube causes the beam emerging from said aperture to be diverted from a radial path outside of said shield electrode.

2. An electron discharge device having a cathode for'emitting electrons and an output anode for receiving electrons from said cathode, a control grid surrounding said cathode and means for forming the electrons into a radially directed beam, a shield electrode positioned around said cathode and grid and provided with an aperture registering with said radially directed beam, a second control electrode surrounding said cathode, first control grid and shield grid and of symmetrical tubular cross section, a plane passing through a transverse axis longitudinally of the tubular control grid and parallel to the axis of said electron beam being displaced laterally with respect to the radial path of said beam whereby during operation of the tube said beam will be diverted from a radial path between the cathode and output anode outside said shield electrode.

ing operation of 3. An electron discharge device having a cathode for supplying electrons, a first control grid surrounding said cathode, and means for forming the electrons from said cathode into radial oppositely directed electron beams, a shield electrode surrounding said cathode and control grid and provided with apertures registering with the oppositely directed radial beams, a tubular second control grid and an anode surrounding said cathode, first control grid and shield electrode and positioned eccentrically with respect to the cathode, first control grid and shield electrode whereby during operation of the tube the resulting electric field will cause the electron beams to be diverted from a radial path to the space between the non-apertured portion of the shield electrode and the second control electrode.

4. An electron discharge device comprising a cathode for emittingelectrons and a tubular anode for receiving electrons, a grid surrounding said cathode, and means for forming the electrons from the cathode into a plurality of pairs of oppositely directed radial beams, an auxiliary anode between said grid and said output anode and in the path of one of said radial beams, and a shield electrode surrounding the auxiliary anode and said grid and cathode and provided with an aperture registering with another of said radial beams, a tubular second control grid surrounding said cathode, control grid and shield electrode and positioned eccentrically thereto whereby durthe tube the radial beam emerging from said aperture will be diverted from a radial path to the space between the non-apertured portions of the shield electrode and the second control grid. I

5. An electron discharge device comprising a cathode for emitting electrons and a tubular output anode for receiving'electrons, a grid surrounding said cathode, and means for forming the electrons from the cathode into a plurality of pairs of oppositely directed radial beams, auxiliary anode rods on opposite sides of the cathode and between said grid and said output anode, one rod being in the path of each of the beams of one of a the pairs of oppositely'directed radial beams, and

a shield electrode surrounding the auxiliary anode rods and said grid and cathode and provided with apertures registering with another of the pairs of oppositely directed radial beams, a tubular second control grid within the output anode and surrounding said cathode, control grid and shield electrode and positioned eccentrically thereto whereby during operation of the tube the radial beams emerging from said apertures will be diverted from a radial path to the space between the non-apertured portions of the shield electrode and the tubular second control grid.

6. An electron discharge device having a cathode surrounded by a control grid, means for forming the electrons from the cathode into a plurality of oppositely directed radial beams, a shield electrode surrounding said grid and cathode'and provided with apertures registering with one of the pairs of oppositely directed radial beams, auxiliary anodes positioned within said shield electrode and between the shield electrode and the control grid and in the paths of another pair of oppositely directed radial beams, a tubular second control electrode and a tubular anode surrounding said cathode, first control grid and shield electrode and positioned eccentrically with respect to said cathode, first control grid and shield electrode for providing an electric field during operation of the tube which will divert the ode and provided with apertures registering with one of the pairs of oppositely directed radial beams, auxiliary anodes positioned within said shield electrode and between the shield electrode and the control grid and in the paths of another pair of oppositely directed radial beams, a tubular second control electrode and a tubular anode surrounding said cathode, first control grid and shield electrode and positioned eccentrically with respect to said cathode, first control grid and shield for providing an electric field during operation of the tube which will divert the radial beams emerging through the apertures in said shield electrode to the space between the nonapertured portions of the shield electrode and the second control grid and auxiliary electrodes positioned in the space between the non-apertured portions of the shield electrode and the second control grid for receiving electrons diverted from the radial path.

ADRIANUS JOHANNES WILHELMUS MARIE VAN OVERBEEK. 

